The present invention relates to take-up reels of the type for winding and paying out an elongated flexible member such as a cable, rope, hose or the like, and which automatically rewind the flexible member when it is released.
The art is replete with applications in which a flexible member such as a cable, rope, hose, electrical cord or the like is wound about a take-up reel for storage when not in use, and which is paid out by unwinding from the take-up reel to the appropriate length as required. A popular application for this arrangement is use of a flexible hose for carrying air, water, oil, grease, and the like from a reservoir to a dispensing nozzle at an automobile service station. For example, in the typical automobile service station, air is delivered from a compressor tank through a long pipe to a spring-loaded take-up reel about which is stored a length of tubular air hose. When air is needed, the air hose is pulled from the reel until the desired length is paid out. When the air hose is no longer in use, the end is released and a torsional spring acting on the hose reel rewinds the hose onto the reel.
The torque exerted by the torsional spring on the take-up reel causes the take-up reel, and with it the payed-out hose, to accelerate as the hose is taken up, with result that the terminal velocity of the hose may be quite high as the last bit of hose is retracted. The sudden stop of the mechanism when the end of the hose is reached can cause damage to the rewind mechanism and/or the hose. Moreover, the whipping action that occurs as a result of the uncontrolled rewinding speed can cause personal injury. Various breaking mechanisms have been proposed for automatically limiting the rewind rate of the take-up reel. For example, U.S. Pat. No. 4,446,884 to Rader, Jr. proposes use of a viscous dampening mechanism coupled between the spool and its support shaft. Being a viscous dampener, the retarding force exerted by the viscous dampener is directly proportional to the rotational speed of the reel. Accordingly, the reel will tend to seek a velocity at which the retarding force is equal to the force exerted on the reel by the torsional spring, such that the spool will attain a constant velocity. The viscous dampener disclosed in Rader, however, is rigidly attached to the support shaft and therefore exerts a retarding force on the hose reel irrespective of whether the hose is being payed-out or being retracted. In most applications, it is not necessary to regulate the speed at which the hose is payed-out. Accordingly, a viscous dampener that operates in both directions such as disclosed by Rader unnecessarily loads the hose as it is being payed-out, potentially leading to premature failure of the hose and/or the rewind mechanism. Accordingly, what is needed is a take-up reel with a viscous clutch that operates only when the hose is being retracted and therefore allows the hose reel to be decoupled from the viscous dampener when the hose is being payed-out.